Mobile concrete mixing trucks are used to mix concrete and to deliver that concrete to a site where the concrete may be required. Generally, the particulate concrete ingredients are loaded at a central depot, and liquid component is added at the central depot and while in transit. The liquid component traditionally includes water, but in more modern applications may also include chemical additives of various types.
A number of patent filings have explored the possibility for monitoring the mixing of concrete, or controlling the process of adding liquid component.
Zandberg et al., U.S. Pat. No. 5,713,663 (the '663 patent), the disclosure of which is hereby incorporated herein by reference, describes a method and apparatus of measuring slump of concrete in a mixing barrel from the driving force required to rotate the mixing barrel. The system monitors the torque loading on the driving means used to rotate the mixing barrel, and adds liquid component in attempt to approach a predetermined minimum torque loading related to the amount of the particulate ingredients in the drum.
Buckelew et al., U.S. Pat. No. 6,484,079 (the '079 patent), the disclosure of which is also hereby incorporated herein by reference, describes a method that remotely monitors and reports sensor data associated with a concrete delivery vehicle. More specifically, the data is collected and recorded at the delivery vehicle, and then reported to a dispatch center upon a ‘transmission event’.
U.S. patent application Ser. No. 10/599,130, filed by the assignee of the present application, discloses an improved slump measurement method, improved liquid management methods, and improved mixture measurement and reporting methods.
U.S. patent application Ser. No. 11/764,832, filed by the assignee of the present application, discloses a concrete truck management and slump measurement system using a temperature sensor mounted to the mixing drum. Specifically, a temperature probe, such as mounted to a hatch door of the drum, senses mixture temperature which may be used to track the level of cure of the mixture and make appropriate adjustments. This system also features an accelerometer sensor and improvements in communication systems and mixture management methods.
U.S. patent application Ser. No. 11/834,002, filed by the assignee of the present application, discloses an improved concrete truck management system in which multiple chemical additives are controllably managed and added to the mixing drum, under either local or remote control. Electronic identification is used to track the additives in use.
While these various systems have been proposed and implemented, improvements continue to be needed, particularly in the use of remote sensors on concrete delivery vehicles.